Pesticides play an important role in controlling agricultural pests and diseases as well as in increasing crop yields. However, the agricultural industry increasingly depends on pesticides, which contaminate soil and water. For example, merely 0.3% of pesticides work on pests, and the remaining 99.7% of pesticides are left on surfaces of crops and in the natural environment including soil and water. Eventually, these pesticides enter rivers, lakes and groundwater through rainfall and irrigation. This results in potential health hazards to humans and other aquatic organisms. Tebuconazole is an important pesticide and widely used in the world. Tebuconazole effectively controls various agricultural diseases such as rust, powdery mildew, net blotch, root rot, Fusarium head blight and smut associated with crops as well as rust, powdery mildew and scab, and other fungal diseases associated with fruits. Currently, tebuconazole has been registered on 65 kinds of crops in more than 50 countries; therefore, related environmental problems are increasingly urgent. Although tebuconazole concentrations in the environment are not high, potential hazards and risks of tebuconazole to the environment cannot be ignored. Therefore, many scholars have studied treatment of tebuconazole in wastewater, and several methods for removal of tebuconazole have been reported. Generally, these methods can be categorized into three main categories.
The first category includes a biochemical-based method, which utilizes microorganism organisms to break tebuconazole structures and turn these structures into small molecules that are less toxic and/or susceptible to be degraded. Although the method is economically applicable, the method has the following disadvantages: (1) Anti-water quality fluctuation capability is weak, and the method cannot afford charges from high pollution loads in wastewater; (2) Microbial degradation of tebuconazole (e.g., taking 3-5 days) is slower than that of conventional techniques such as adsorption and chemical oxidation based methods. Although it has been reported of strains capable of screening and degrading tebuconazole (Hongping Wu et al., Tebuconazole pesticide screening degrading bacteria and their degradation of performance, pesticide, Feb. 2013 10). However, Hongping Wu et al. does not identify the type of bacteria for removal of tebuconazole, provides no embodiments using the strains as well as systems implementing the method. Therefore, methods for removal of tebuconazole using bio-degradable techniques have not been reported.
The second category includes an adsorption-based method, which separates tebuconazole from water without altering its chemical structure. Although the absorption-based method is the most common and more efficient approach in the laboratory or the industry, this method has a serious problem: desorption solutions for resin regeneration. Thus, effective desorption disposals have to be used; otherwise secondary pollution will happen. Currently, research has been focused on the adsorption method implementing activated carbon on adsorption of tebuconazole; however, implementations of resin adsorption techniques to remove tebuconazole from wastewater has not been reported.
The third category includes a chemical-oxidation-based method, which implements chemical-oxidation processes to remove tebuconazole from water. This method has been patented (e.g., An immobilized microorganism treatment of organic phosphorus pesticide wastewater use, Publication Number: CN103102015A). However, this method requires adding more chemical agents, involves complex operations, and incurs high operating costs. Further, this method is not efficient and economically applicable to remove tebuconazole in a low concentration from wastewater. In addition to adding excessive chemical agents, the method may further deteriorate quality of water and increase toxicity of water.
To overcome these disadvantages, there is a need for developing systems and methods for efficiently remove tebuconazole in water.